Electrons are one of the fundamental particles that make up atoms. They are negatively charged particles that are found in the outermost shell, or energy level, of an atom. This outer shell is known as the electron cloud, or electron shell.The number of electrons in the outer shell of an atom is known as its valence. Atoms with a full outer shell are considered to be stable and are less likely to participate in chemical reactions. Atoms with less than a full outer shell, or a non-stable valence, are more likely to participate in chemical reactions in order to acquire or lose electrons and achieve a stable valence.The arrangement of electrons in the shells of an atom is determined by the atom's atomic number. The atomic number represents the number of protons found in the nucleus of an atom. The number of electrons in the atom is always equal to the number of protons, which means that atoms are always neutral.Electrons are arranged in shells around the nucleus of an atom, with the innermost shell holding the least number of electrons and the outermost shell holding the most. The number of electrons in each shell is determined by the maximum number of electrons that can be held in that shell, which is determined by the electron capacity of the shell.The electrons in the outermost shell of an atom are responsible for chemical reactions and bonding. Atoms will gain or lose electrons from the outermost shell in order to achieve a stable electron configuration, which is known as the octet rule. This results in the formation of chemical bonds between atoms, which ultimately leads to the formation of molecules and compounds.In conclusion, Electrons are negatively charged particles that are found in the outermost shell, or energy level, of an atom, known as the electron cloud or electron shell. The number of electrons in the outer shell of an atom is known as its valence, atoms with a full outer shell are considered to be stable, whereas atoms with less than a full outer shell are more likely to participate in chemical reactions. The arrangement of electrons in the shells of an atom is determined by the atom's atomic number, the electrons in the outermost shell of an atom are responsible for chemical reactions and bonding, ultimately resulting in the formation of molecules and compounds.